Refactor process table

kernel/src/fs/procfs/mod.rs

@@ -130,7 +130,7 @@ impl DirOps for RootDirOps {
         cached_children
             .put_entry_if_not_found("meminfo", || MemInfoFileOps::new_inode(this_ptr.clone()));
 
-        for process in process_table::process_table().iter() {
+        for process in process_table::process_table_mut().iter() {
             let pid = process.pid().to_string();
             cached_children.put_entry_if_not_found(&pid, || {
                 PidDirOps::new_inode(process.clone(), this_ptr.clone())

kernel/src/process/kill.rs

@@ -105,7 +105,7 @@ pub fn tgkill(tid: Tid, tgid: Pid, signal: Option<UserSignal>, ctx: &Context) ->
 /// if it is authorized to send the signal to the target group.
 pub fn kill_all(signal: Option<UserSignal>, ctx: &Context) -> Result<()> {
     let current = current!();
-    for process in process_table::process_table().iter() {
+    for process in process_table::process_table_mut().iter() {
         if Arc::ptr_eq(&current, process) || process.is_init_process() {
             continue;
         }

kernel/src/process/process_table.rs

@@ -14,43 +14,63 @@ use crate::{
     prelude::*,
 };
 
-static PROCESS_TABLE: Mutex<BTreeMap<Pid, Arc<Process>>> = Mutex::new(BTreeMap::new());
+static PROCESS_TABLE: Mutex<ProcessTable> = Mutex::new(ProcessTable::new());
 static PROCESS_GROUP_TABLE: Mutex<BTreeMap<Pgid, Arc<ProcessGroup>>> = Mutex::new(BTreeMap::new());
-static PROCESS_TABLE_SUBJECT: Subject<PidEvent> = Subject::new();
 static SESSION_TABLE: Mutex<BTreeMap<Sid, Arc<Session>>> = Mutex::new(BTreeMap::new());
 
 // ************ Process *************
-
 /// Gets a process with pid
 pub fn get_process(pid: Pid) -> Option<Arc<Process>> {
-    PROCESS_TABLE.lock().get(&pid).cloned()
+    PROCESS_TABLE.lock().get(pid).cloned()
 }
 
-pub(super) fn process_table_mut() -> MutexGuard<'static, BTreeMap<Pid, Arc<Process>>> {
+pub fn process_table_mut() -> MutexGuard<'static, ProcessTable> {
     PROCESS_TABLE.lock()
 }
 
-/// Acquires a lock on the process table and returns a `ProcessTable`.
-pub fn process_table() -> ProcessTable<'static> {
-    ProcessTable {
-        inner: PROCESS_TABLE.lock(),
+/// Process Table.
+pub struct ProcessTable {
+    inner: BTreeMap<Pid, Arc<Process>>,
+    subject: Subject<PidEvent>,
+}
+
+impl ProcessTable {
+    pub const fn new() -> Self {
+        Self {
+            inner: BTreeMap::new(),
+            subject: Subject::new(),
         }
     }
 
-/// A wrapper for the mutex-protected process table.
-///
-/// It provides the `iter` method to iterator over the processes in the table.
-pub struct ProcessTable<'a> {
-    inner: MutexGuard<'a, BTreeMap<Pid, Arc<Process>>>,
+    pub fn get(&self, pid: Pid) -> Option<&Arc<Process>> {
+        self.inner.get(&pid)
+    }
+
+    pub fn insert(&mut self, pid: Pid, process: Arc<Process>) {
+        self.inner.insert(pid, process);
+    }
+
+    pub fn remove(&mut self, pid: Pid) {
+        self.inner.remove(&pid);
+        self.subject.notify_observers(&PidEvent::Exit(pid));
     }
 
-impl ProcessTable<'_> {
     /// Returns an iterator over the processes in the table.
     pub fn iter(&self) -> ProcessTableIter {
         ProcessTableIter {
             inner: self.inner.values(),
         }
     }
+
+    /// Registers an observer which watches `PidEvent`.
+    pub fn register_observer(&self, observer: Weak<dyn Observer<PidEvent>>) {
+        self.subject.register_observer(observer, ());
+    }
+
+    /// Unregisters an observer which watches `PidEvent`.
+    pub fn unregister_observer(&self, observer: &Weak<dyn Observer<PidEvent>>) {
+        self.subject.unregister_observer(observer);
+    }
 }
 
 /// An iterator over the processes of the process table.
@@ -97,12 +117,12 @@ pub(super) fn session_table_mut() -> MutexGuard<'static, BTreeMap<Sid, Arc<Sessi
 
 /// Registers an observer which watches `PidEvent`.
 pub fn register_observer(observer: Weak<dyn Observer<PidEvent>>) {
-    PROCESS_TABLE_SUBJECT.register_observer(observer, ());
+    PROCESS_TABLE.lock().register_observer(observer);
 }
 
 /// Unregisters an observer which watches `PidEvent`.
 pub fn unregister_observer(observer: &Weak<dyn Observer<PidEvent>>) {
-    PROCESS_TABLE_SUBJECT.unregister_observer(observer);
+    PROCESS_TABLE.lock().unregister_observer(observer);
 }
 
 #[derive(Copy, Clone)]

kernel/src/process/wait.rs

@@ -118,6 +118,6 @@ fn reap_zombie_child(process: &Process, pid: Pid) -> ExitCode {
         }
     }
 
-    process_table_mut.remove(&child_process.pid());
+    process_table_mut.remove(child_process.pid());
     child_process.exit_code()
 }

kernel/src/syscall/set_get_priority.rs

@@ -69,7 +69,7 @@ fn get_processes(prio_target: PriorityTarget) -> Result<Vec<Arc<Process>>> {
         }
         PriorityTarget::User(uid) => {
             // Get the processes that are running under the specified user
-            let processes: Vec<Arc<Process>> = process_table::process_table()
+            let processes: Vec<Arc<Process>> = process_table::process_table_mut()
                 .iter()
                 .filter(|process| {
                     let Some(main_thread) = process.main_thread() else {